UM vs. UIM: What's the Difference?
Uninsured motorist (UM) and underinsured motorist (UIM) coverage solve two different problems — a driver with no insurance, and a driver with not enough. Here's how each works and why you need both.
Two Coverages, Two Different Problems
Uninsured and underinsured motorist coverage are often sold together as "UM/UIM," but they respond to two distinct situations. Understanding the difference helps you make sure you're actually protected against both.
Uninsured Motorist (UM)
UM coverage applies when the at-fault driver has no liability insurance at all. This includes:
- A driver who never bought a policy
- A driver whose policy lapsed for non-payment
- In most states, a hit-and-run driver who is never identified
When that driver injures you, there's no policy to collect from — so your own UM coverage steps in and pays what the at-fault driver should have.
Underinsured Motorist (UIM)
UIM coverage applies when the at-fault driver has insurance, but not enough. Picture a serious crash with $80,000 in medical bills, caused by a driver carrying the $25,000 state minimum. Their policy pays $25,000 — and without UIM, the remaining $55,000 is your problem.
UIM fills that gap, paying the difference between the at-fault driver's limits and your losses, up to your UIM limit.
Why You Need Both
UM and UIM cover the two most common ways an at-fault driver leaves you holding the bill: they had nothing, or they had too little. Carrying only one leaves a hole. A complete policy carries both, ideally at limits that match your real exposure — your income, your assets, and your medical risk.
How the Limits Work
- UM/UIM limits are usually written like liability limits — e.g., $100,000 per person / $300,000 per accident.
- Many experts suggest matching your UM/UIM limits to your liability limits, so you're as protected from others as you are protecting them.
We help drivers compare their current UM and UIM limits against their actual risk and quote stronger coverage. [Get a quote](/quote) to review yours.
What's Covered
Frequently Asked Questions
Yes. UM only helps when the at-fault driver has no insurance at all. UIM is what helps when they have insurance but their limits are too low to cover your injuries — an extremely common situation given how many drivers carry only state-minimum limits.
A common guideline is to match your UM/UIM limits to your liability limits, so you're as protected from others as you are protecting them. The right number depends on your income, assets, and medical exposure — we help you choose and quote it.